Crustal and Upper Mantle Structure of South America

The crust and upper mantle beneath South America exhibit remarkable heterogeneity in thickness, composition and rheological properties. Continental cratons such as the Amazon, São Francisco, Paranapanema and Rio de la Plata domains are underlain by thick lithospheric roots extending to depths of 200–300 km, whereas adjacent mobile belts and sedimentary basins often feature thinner crust and attenuated mantle lid. The Moho discontinuity, marking the crust–mantle boundary, varies from roughly 30 km beneath continental margins to over 50 km beneath elevated plateaux. Subduction of the Nazca plate beneath the western margin generates strong anisotropic fabrics in the upper mantle and contributes to crustal deformation along the Andes chain. Major suture zones – including the Western Paraná Suture and Transbrasiliano Lineament – delineate ancient collisional boundaries and influence present-day isostatic and geochemical signatures. Variations in lithospheric temperature, density and composition have been mapped through seismic tomography, gravity inversion and petrophysical modelling, revealing metasomatic modification by mantle plumes, dynamic thinning by subduction processes and preservation of cold, buoyant roots. Understanding this architecture is vital for natural resource exploration, seismic hazard assessment and geodynamic reconstructions of continental assembly and break-up.

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Crustal and Upper Mantle Structure of South America publication trend

The graph below shows the total number of articles in crustal and upper mantle structure of south america across all publications each year (not limited to Nature Index journals).

Technical terms

Moho discontinuity: The boundary separating Earth’s crust from the upper mantle, identified by a sharp increase in seismic velocity.

Craton: An ancient, stable block of continental lithosphere that has remained largely undeformed over geological timescales.

Lithospheric root: The thick, cold, rigid portion of the lithosphere extending beneath cratons into the upper mantle.

Bouguer anomaly: A gravity measurement corrected for topography and the gravitational effect of surface masses, used to infer subsurface density variations.

Joint inversion: An integrated modelling approach that simultaneously fits multiple geophysical datasets (e.g., seismic velocities, gravity, topography) to derive unified subsurface models.

References

1. Mantle anisotropy and asthenospheric flow around cratons in southeastern South America. Geophysical Journal International (2018).
2. A Thermo‐Compositional Model of the Cratonic Lithosphere of South America. Geochemistry Geophysics Geosystems (2021).
3. Lithosphere density structure of southeastern South America sedimentary basins from the analysis of residual gravity anomalies. Frontiers in Earth Science (2023).
4. Thermo‐Compositional Structure of the South American Platform Lithosphere: Evidence of Stability, Modification, and Erosion. Geochemistry Geophysics Geosystems (2022).